Doctors typically do not recommend using both single-ingredient Tylenol and DayQuil at the same time, as it increases the risk of adverse events like liver damage due to accidental overdoses.

Source: https://fortune.com/well/2023/04/21/are-over-the-counter-medications-safe-pharmacy-hospitalization/

“I was super sick that day and I was downing Sudafed and DayQuil to try to keep myself awake and tried my best to not hack up a lung,” Bobby responds, admitting the cards weren’t exactly in his favour on the big day.

Source: https://www.huffingtonpost.co.uk/entry/bobby-berk-queer-eye-interview_uk_6493247de4b02f808ab2e327

Sales of cold and flu treatments shot up 30% in that time — meaning a merry Christmas for the makers of Mucinex and DayQuil.

Source: https://gorgenewscenter.com/2023/12/25/post-covid-sick-shaming-pressuring-millions-to-rely-on-over-the-counter-medications/